Semiconductor processing in the fabrication of integrated circuitry typically includes the deposition of layers on semiconductor substrates. Exemplary processes include physical vapor deposition (PVD), and chemical vapor deposition (CVD) which herein includes atomic layer deposition (ALD). With typical ALD, successive mono-atomic layers are adsorbed to a substrate and/or reacted with the outer layer on the substrate, typically by successive feeding of different precursors to the substrate surface.
Chemical and physical vapor depositions can be conducted within chambers or reactors which retain a single substrate upon a wafer holder or susceptor. The chambers include internal walls which can undesirably have deposition product deposited thereupon in addition to the substrate. This is particularly problematic in ALD and other CVD processes. One existing method of protecting or preserving the internal chamber walls is to shield such from the deposition material with one or more removable liners. These liners might be received immediately adjacent or against the internal chamber walls. Alternately, the liners might be displaced therefrom, thereby defining a significantly reduced volume chamber, or subchamber, within which the substrate is received for deposition. One advantage of using liners is that they can be periodically replaced with new or cleaned liners, thereby extending the life of the deposition chambers. Further and regardless, the spent liners can typically be removed and replaced much more quickly than the time it would take to clean the internal chamber walls at a given cleaning interval.
A typical chemical vapor deposition apparatus includes a deposition chamber which connects to a transfer chamber through a passageway. Substrates are transferred into and out of the deposition chamber by a robotic arm assembly which passes through the passageway from the transfer chamber. Typically, the deposition chamber and transfer chamber are maintained at subatmospheric pressure in operation. The deposition chamber is typically maintained at a slightly lower subatmospheric pressure than is the transfer chamber. Once positioned within the deposition chamber, a mechanical gate or door received within the transfer chamber is moved to a sealing position to cover the passageway within the transfer chamber. Further, some passageways are provided with a plurality of inert gas ports through which inert purge gas is emitted, at least during deposition, to form an inert gas curtain within the passageway. A desired intent or effect of the inert gas curtain is to preclude deposition product from depositing within the passageway. The inert gas forming the curtain is ultimately drawn to within the deposition chamber and passes out the vacuum foreline from the chamber.
Unfortunately, the flow of inert purge gas from the passageway can adversely impact the deposition upon the substrate received therewithin. For example, some of the inert gas will inherently be caused to flow over the wafer surface from the side of the substrate which is proximate the passageway. Other sides/edges of the wafer surface are not subjected to the same inert gas flow. This can have an adverse effect on the deposition. One prior art method of attempting to alleviate the impact from such inert purge gas flow is to provide inert purge gas injection into the deposition chamber proximate the other edges/sides of the substrate.
The invention was motivated in addressing or overcoming the above-described drawbacks, although it is in no way so limited. The invention is only limited by the accompanying claims as literally worded without interpretative or other limiting reference to the specification or drawings, and in accordance with the doctrine of equivalents.